The 30-year-old centre back, who scored against the Tigers at the KCOM Stadium earlier this month, completed the move earlier today.
After starting his career with Brighton & Hove Albion, where he played more than 180 times, Elphick moved along the south coast to Bournemouth and helped the Cherries win promotion to the Premier League during a four-year stay.
He joined Aston Villa in June 2016 and spent part of last season on loan with Reading. He’s played three times for Villa this season, including that opening weekend win against Nigel Adkins’ side.
Speaking about his move, Elphick said: “I’m excited about a new challenge and to be working for Nigel Adkins and with this group of players.
“The Head Coach is looking to create a hard-working culture here but there is also some real talent within the squad and I’m looking forward to being a part of this group.”